Transparent material light-emitting module with two reflection faces

ABSTRACT

A light-emitting module, notably for a motor vehicle, including a translucent or transparent material body having an entry face for light rays produced by one or more light sources, a first reflection face with an edge for cutting off the rays coming from the entry face, a second reflection face for reflecting toward the exit face rays coming from the first reflection face, and an exit face for the light rays in an exit beam along an optical axis of the module. The invention also relates to a headlight including at least one such light-emitting module.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.15/228,257, filed Aug. 4, 2016, which claims priority to the FrenchPatent Application No. 1557584, filed Aug. 6, 2015. Each of theabove-reference applications is hereby incorporated herein by referencein its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to the field of lighting, notably lighting for amotor vehicle. The invention also relates to a headlight including amodule of this kind.

2. Description of the Related Art

The published patent document FR 3 010 772 A1 discloses a lightingmodule with a transparent material body having an entry face for thelight produced by one or more light sources, a reflection face with acut-off edge and an exit face of the rays. The entry face includes acavity formed at one end of the module, in the transparent material, anddelimited by a circular surface forming a diopter adapted to deflect theincoming rays towards the exterior and peripheral surface of the body.The rays are then reflected at the exterior surface, by application ofthe principle of total internal reflection, to converge toward thecut-off edge. The exit face is generally convex and is at the oppositeend of the module. The reflection face is formed by a notch formed in alateral portion of the transparent material, between the entry and exitfaces. The edge in the recess of the notch forms the cut-off edge forthe rays and the face of the notch situated beside the entry face formsa reflection face by virtue of the principle of total internalreflection. This reflection face is commonly referred to as the “bender”in that it “bends” some of the rays toward the bottom of the beam. Therays coming from the entry face propagate in the transparent materialessentially along the longitudinal and optical axis of the module. Mostof the rays pass the cut-off edge without being reflected and exit viathe exit face. Some of the rays encounter the reflection or bender facedisposed in front of the cut-off edge, where they are reflected towardan upper portion of the transparent body. These rays then encounter theexit face with a high angle of incidence. They are therefore subjectedthere to strong refraction and are directed toward a lower portion ofthe light beam. Thus, the edge of the bender makes it possible toproduce a horizontal cut off in the light beam. This module isbeneficial in that it makes it possible to produce with a very smallnumber of components a high-performance light beam with a cut-off.However, it has the disadvantage that it requires a certain amount ofspace along the optical axis. In fact the transparent body extends alongits longitudinal axis essentially along the optical axis of the module.Moreover, because of its shape the exit face cannot serve as a stylingface, i.e. one directly visible from the outside of the lighting deviceincluding the module. It is therefore necessary to provide an additionalstyling surface, which also increases the overall size.

SUMMARY OF THE INVENTION

The invention has the objective of alleviating at least one problem ofthe prior art, in this instance the prior art mentioned above. To bemore precise, the invention has the objective of proposing alight-emitting module that is compact, in particular along its opticalaxis.

The invention consists in a light-emitting module, notably for a motorvehicle, including a translucent or transparent material body having anentry face for light rays produced by one or more light sources; a firstreflection face with an edge for cutting off the rays coming from theentry face; an exit face for light rays in an exit beam along an opticalaxis of the module; noteworthy in that it further includes a secondreflection face for reflecting toward the exit face rays coming from thefirst reflection face.

In accordance with one advantageous embodiment of the invention, thefirst reflecting face forms a diopter adapted to reflect by theprinciple of total internal reflection some of the rays coming from theentry face.

In accordance with one advantageous embodiment of the invention, thefirst reflection face forms an angle between 5° and 40° inclusive withthe mean direction of the light beams propagating from the entry face tothe reflection face.

In accordance with one advantageous embodiment of the invention, thefirst reflection face comprises two adjacent portions forming an edgedirected toward the second reflection face and/or the exit face, theportions forming, transversely to the edge, a convex profile.

In accordance with one advantageous embodiment of the invention, thecut-off edge is formed by the intersection of the first reflection facewith an intermediate face situated between the first reflection face andthe second reflection face, the first reflection face and theintermediate face forming a concave profile.

In accordance with one advantageous embodiment of the invention, theintermediate face comprises two adjacent portions forming an edgedirected toward the second reflection face, the portions forming,transversely to the edge, a convex profile.

In accordance with one advantageous embodiment of the invention, thesecond reflection face extends between the intermediate face and theexit face.

In accordance with one advantageous embodiment of the invention, thesecond reflection face is generally curved and convex.

In accordance with one advantageous embodiment of the invention, thesecond reflection face forms a diopter adapted to reflect, by theprinciple of total internal reflection, the rays coming from the firstreflection face.

In accordance with one advantageous embodiment of the invention, thebody includes a first portion extending from the entry face as far asthe second reflection face in a principal direction forming an anglebetween 60° and 120° inclusive with the optical axis.

In accordance with one advantageous embodiment of the invention, themodule includes a second portion extending from the second reflectionface as far as the exit face along the optical axis.

In accordance with one advantageous embodiment of the invention, theentry face includes one or more collimators adapted to deflect the lightrays from one or more respective light sources so as to form one or morebeams of rays directed toward the second reflection face and passing infront of the cut-off edge.

In accordance with one advantageous embodiment of the invention, thecollimator, or each of the collimators, is formed by a protuberance ofthe body with a circular exterior surface preferably having anelliptical profile, the protuberance including a cavity adapted toreceive the corresponding light source.

In accordance with one advantageous embodiment of the invention, theentry face includes one or more collimators adapted to deflect the lightrays from one or more respective light sources toward a convergencepoint or segment situated on the cut-off edge.

In accordance with one advantageous embodiment of the invention, thecollimator or each of the collimators is formed by a protuberance of thebody having a circular exterior surface having an elliptical profile anda cavity adapted to receive the corresponding light source.

In accordance with one advantageous embodiment of the invention, thereare at least three collimators and they form on the entry face at leastone row extending perpendicularly to the optical axis.

In accordance with one advantageous embodiment of the invention, themodule includes the light sources, the sources being of thesemiconductor light source type, for example of the light-emitting diodetype, disposed on a common board.

In accordance with one advantageous embodiment of the invention, theexit beam is a lighting beam with a horizontal or vertical cut-off.

The invention also consists in a headlight for a motor vehicle includinga housing and at least one light-emitting module, noteworthy in that thelight-emitting module is one in accordance with the invention.

In accordance with one advantageous embodiment of the invention, theheadlight includes two of the light-emitting modules disposed side byside and the exit beams of which are superposed, one of the modulesforming an extended beam with a generally straight cut-off and the otherforming a narrow beam with a horizontal cut-off with a kink.

In accordance with one advantageous embodiment of the invention, theexit face of the light-emitting module is a styling surface, i.e. asurface visible from the outside of the headlight.

The measures of the invention are beneficial in that they make itpossible to produce a light-emitting module that is particularly compactin the direction of the optical axis, i.e. the longitudinal axis of thevehicle. The use of a dioptric bender, i.e. with the first reflectionface reflecting the rays by the principle of total internal reflection,is notably advantageous in that it renders the module more tolerant tofocusing defects. Moreover, the use of a plurality of collimators on theentry face makes it possible to compose the light beam and thereforeconfers great flexibility in the implementation of different functions.Moreover, the module has a common exit face, which has advantages interms of aesthetics and the precision of the total beam resulting fromthe addition of the beams produced by the various collimators.

These and other objects and advantages of the invention will be apparentfrom the following description, the accompanying drawings and theappended claims.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Other features and advantages of the present invention will be betterunderstood with the aid of the description and the drawings, in which:

FIG. 1 is a perspective view of a light-emitting module in accordancewith the invention;

FIG. 2 is a rear perspective view of the module from FIG. 1;

FIG. 3 is a view in section on a longitudinal median plane of the modulefrom FIGS. 1 and 2;

FIG. 4 is a perspective detail view of the lower portion of the modulefrom FIGS. 1 to 3;

FIG. 5 is a diagrammatic representation of the path of some of the raysfrom the module from FIGS. 1 to 4; and

FIG. 6 is a diagrammatic representation of the path of the rays from themodule of FIGS. 1 to 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, relative terms such as “top”, “upper”,“bottom”, “lower”, “front” and “rear” are to be understood in relationto the orientation of the light-emitting module 2 as shown in thefigures, it being understood that in practice the light-emitting module2 can assume other orientations.

FIGS. 1 to 4 illustrate a light-emitting module 2 in accordance with theinvention. The light-emitting module 2 essentially comprises a body 4and light sources (not represented).

The body 4 is made mainly, preferably totally, from a transparent ortranslucent material. That material may be glass or preferably plastic,such as polycarbonate (PC) in particular.

The body 4 includes an entry face 6 for the light produced by the lightsources. The latter may be light-emitting diodes or of the laser type.The body 4 also includes a first reflection face 8 intended to reflectonly some of the rays, a second reflection face 10, intended to reflectvirtually all of the rays, and an exit face 12.

The entry face 6 may include collimators 61 and 62. They are morevisible in FIG. 4. Here they may form protuberances projecting from thebody 4 and forming an exterior surface that may be generally circular.Each of these protuberances includes a cavity intended to receive one ofthe light sources. The interior surface of the protuberances delimitingthe cavity forms a first diopter with the surrounding air, causingrefraction of the rays passing through it. The exterior surface of theprotuberances forms a second diopter with the surrounding air. As afunction of the angle of incidence of the rays encountering it, thelatter may be reflected by the principle of total internal reflection.In fact, in geometrical optics, the phenomenon of total internalreflection occurs if a light ray arrives at the surface of separation oftwo media with different optical indices with an angle of incidencegreater than a critical value: there is then no longer any transmittedrefracted ray and there remains only a reflected ray. This limitingangle of incidence ϑ is obtained by application of the Snell-Descarteslaw, namely

${\theta = {\sin^{- 1}\frac{n_{2}}{n_{1}}}},$where n₂ is the refractive index of air and n₁ is the refractive indexof the transparent or translucent material forming the protuberance. Fora material such as polycarbonate with a refractive index of the order of1.591, the limiting refraction angle ϑ is of the order of 39°. Theexterior surface of the protuberances forming the second diopters mayhave a parabolic or elliptical profile.

The body 4 of the light-emitting module 2 includes an intermediate face16 between the first reflection face 8 and the second reflection face10. As can be seen in FIGS. 2 and 3 in particular, the intermediate face16 and the first reflection face 8 have a concave profile and form attheir intersection an edge 14 cutting off the rays propagating in thebody 4. In fact, most of the rays propagate from the entry face 6 to thesecond reflection face 10, passing in front of the cut-off edge 14, i.e.without undergoing intermediate reflection. Now some of the rays comingfrom the entry face 6 encounter the first reflection face 8, to be moreprecise the portion of the face that is adjacent the cut-off edge 14.Those rays are then reflected, advantageously by the principle of totalinternal reflection (described above in relation to the protuberances 61and 62 of the entry face 6). In this case, the first reflection face 8does not need to receive a reflective treatment. The effect of thereflection of some of the rays by the first reflection face 8 is todirect those rays toward an upper portion of the second reflection face10 and/or of the exit face 12, with high angles of incidence having theeffect of refracting these rays toward a bottom portion of the lightbeam. In conjunction with the cut-off edge 14, the first reflection face8 is commonly referred to as a “bender”, in that it “bends” some of therays toward a bottom portion of the light beam, thus providing a beamhorizontal cut-off function.

The first reflection face 8 advantageously forms an angle between 5° and40° inclusive with the mean direction of the light beams propagatingfrom the entry face 6 to the first reflection face 8.

In FIG. 2, it can be seen that the first reflection face 8 may comprisetwo adjacent portions 81 and 82, those two portions forming an edge 83.The same applies to the intermediate face 16, which may likewisecomprise two portions 161 and 162 forming an edge 163. The two edges 83and 163 are advantageously aligned and adjacent end-to-end. As a result,in this configuration, the cut-off edge 14 is not rectilinear butconstituted of two end-to-end adjacent segments.

The second reflection face 10 may be generally curved, here convex asseen from the outside of the body 4. The same applies to the exit face12. The second reflection face 10 advantageously reflects the rays bythe principle of total internal reflection (described above in relationto the collimators or protuberances 61 and 62 of the entry face 6). Inthis case, the second reflection face 10 does not need to receive areflective treatment.

Referring to FIG. 3, the body 4 may include a first portion 41 extendinggenerally along a longitudinal axis that is generally transverse,advantageously perpendicular, to the entry face 6. The angle formed bythese two axes is advantageously between 60° and 120° inclusive. Therays therefore generally propagate along the longitudinal axis 18, fromthe entry face 6 as far as the second reflection face 10, some of thembeing reflected at the first reflection face 8. The body 4 may equallyinclude a second portion 42 extending transversely to the first portion41 and generally along the optical axis 20. The latter represents themean direction of the light rays leaving the exit face 12.

FIGS. 5 and 6 illustrate the principle of propagation of the rays insidethe body 4 of the light-emitting module 2 from FIGS. 1 to 4.

In FIG. 5 it can be seen that the light rays produced by the collimator61 converge at a focal point or segment passing through the cut-off edge14. This means that the majority of the rays coming from the focuscollimator 61 in question pass in front of or over the cut-off edge 14without being reflected. Those rays then encounter the second reflectionface 10 to be reflected here in the direction of the exit face 12. Thecurvatures of the second reflection face 10 and/or the exit face 6 arecalculated to form a light beam along the optical axis 20 of thelight-emitting module 2. Here, the rays coming from the collimator orcollimators 61 form the portion 22 of the beam, namely the upper portionwith the cut-off edge 14.

FIG. 6 shows the path of the light rays produced by the collimator 61,as shown in FIG. 5, with, additionally, the light rays produced by thecollimator 62. See the description of FIG. 5 for the rays from thecollimator 61. It can be seen that the rays produced by the collimator62 are generally parallel to one another and most pass in front of thecut-off edge 14. As can be seen in FIG. 6, these rays encounter thesecond reflection face 10 with lower angles of incidence than the rayscoming from the other collimator 61. These rays are then reflected indirections such that, after refraction through the exit face 12, theyform the lower portion 24 of the light beam.

The conjugation of the two types of collimators 61 and 62 thereforemakes it possible to form a beam with a controlled cut-off and ahomogeneous and powerful lower portion.

As can be seen in FIGS. 1 to 4, the entry face 6 may include a pluralityof focus collimators 61 and a plurality of collimators 62. These twotypes of collimators 61 and 62 are disposed in rows extendingtransversely to the optical axis 20. Each of the collimators 61 and 62of a row therefore makes it possible to contribute to the formation ofthe beam in a lateral direction. The focus collimator or collimators 61is/are advantageously disposed behind the other collimators 62.

In FIGS. 5 and 6 it can be seen that the cut-off produced appears to begenerally rectilinear. Now, the regulations impose what is commonlyreferred to as a “kink”. The kink of the cut-off may be produced by thelight-emitting module 2 by means of an appropriate profile of thecut-off edge 14. Alternatively, the kink may be produced by anotherlight-emitting module 2 disposed beside the light-emitting module 2 fromFIGS. 1 to 6, the beam from which is added to the beam produced by theprincipal light-emitting module 2.

The light sources of the light-emitting module or modules 2 may bedisposed on a common support, such as a printed circuit board, forexample.

One or more light-emitting modules 2 as described above may beintegrated into a housing in order to produce a headlight.

While the system, apparatus, process and method herein describedconstitute preferred embodiments of this invention, it is to beunderstood that the invention is not limited to this precise system,apparatus, process and method, and that changes may be made thereinwithout departing from the scope of the invention which is defined inthe appended claims.

What is claimed is:
 1. A light-emitting module for a motor vehicle,including a translucent or transparent material body comprising: anentry face for entry light rays produced by one or more light sourcesand entering said body; a first reflection face with a cut-off edge forcutting off the entry light rays coming from said entry face such that afirst portion of the entry light rays is reflected from the firstreflection face toward a second reflection face, and a second portion ofthe entry light rays passes by the cut-off edge without being reflectedby the first reflection face and is directly incident of said secondreflection face; an exit face for providing exit light rays in an exitbeam along an optical axis of said light-emitting module, wherein saidsecond reflection face reflects said first portion of the entry lightrays coming from the first reflection face toward the exit face, andreflects said second portion of the entry light rays coming from theentry face toward the exit face.
 2. The light-emitting module accordingto claim 1, wherein said first reflection face forms a diopter adaptedto reflect, by a principle of total internal reflection, said firstportion of the entry light rays coming from said entry face.
 3. Thelight-emitting module according to claim 1, wherein said firstreflection face forms an angle between 5° and 40° inclusive, withrespect to a mean direction of the entry light rays propagating fromsaid entry face to said first reflection face.
 4. The light-emittingmodule according to claim 1, wherein said first reflection facecomprises two adjacent portions forming a first edge, said two adjacentportions forming, transversely to said first edge, a convex profile. 5.The light-emitting module according to claim 1, wherein said cut-offedge is formed by an intersection of said first reflection face with anintermediate face situated between said first reflection face and saidsecond reflection face, said first reflection face and said intermediateface forming a concave profile.
 6. The light-emitting module accordingto claim 5, wherein said intermediate face comprises two adjacentportions forming a second edge, said two adjacent portions forming,transversely to second said edge, a convex profile.
 7. Thelight-emitting module according to claim 5, wherein said secondreflection face extends between said intermediate face and said exitface.
 8. The light-emitting module according to claim 1, wherein saidsecond reflection face is generally curved and convex.
 9. Thelight-emitting module according to claim 1, wherein said secondreflection face forms a diopter adapted to reflect, by a principle oftotal internal reflection, said first portion of the entry light rayscoming from said first reflection face.
 10. The light-emitting moduleaccording to claim 1, wherein said translucent or transparent materialbody includes a first portion extending from said entry face to saidsecond reflection face in a principle direction forming an angle ofbetween 60° and 120°, inclusive, with respect said optical axis.
 11. Thelight-emitting module according to claim 10, wherein said translucent ortransparent material body includes a second portion extending from saidsecond reflection face to said exit face along said optical axis. 12.The light-emitting module according to claim 1, wherein said entry faceincludes one or more collimators adapted to deflect the light rays fromone or more respective light sources so as to form one or more beams ofrays directed toward said second reflection face and passing in front ofsaid cut-off edge.
 13. The light-emitting module according to claim 12,wherein at least one of said one or more collimators is formed by aprotuberance of said translucent or transparent material body with acircular exterior surface preferably having an elliptical profile, saidprotuberance including a cavity adapted to receive a corresponding lightsource.
 14. The light-emitting module according to claim 1, wherein saidentry face includes one or more collimators adapted to deflect the lightrays from one or more light sources, respectively, toward a convergencepoint or segment situated on said cut-off edge.
 15. The light-emittingmodule according to claim 14, wherein at least one of said one or morecollimators is formed by a protuberance of said translucent ortransparent material body having a circular exterior surface having anelliptical profile and a cavity adapted to receive a corresponding lightsource.
 16. The light-emitting module according to claim 1, wherein anexit beam is a lighting beam with a horizontal or vertical cut-off. 17.A headlight for a motor vehicle including a housing and at least onelight-emitting module, wherein said at least one light-emitting moduleaccording to claim
 1. 18. The headlight according to claim 17, whereinsaid exit face of said at least one light-emitting module is a stylingsurface.
 19. The light-emitting module according to claim 2, whereinsaid first reflection face forms an angle between 5° and 40° inclusivewith a mean direction of the light rays propagating from said entry faceto said reflection face.
 20. The light-emitting module according toclaim 2, wherein said first reflection face comprises two adjacentportions forming an edge directed toward said second reflection faceand/or said exit face, said two adjacent portions forming, transverselyto said edge, a convex profile.